Device and method for assessing perfusion failure in a patient during endotracheal intubation

Abstract

A device and method are provided for assessing impairment of blood circulation in a patient, such as that in perfusion failure, wherein the patient requires mechanical ventilatory support. The invention involves measurement of PCO 2 (partial pressure of carbon dioxide) within the lower respiratory tract of the patient, using a device that includes an endotracheal breathing tube for introducing air from an air supply pump into a patient's lungs, wherein a carbon dioxide sensor is provided as an integral part of that device, i.e., is physically connected to the endotracheal breathing tube in a manner that allows for PCO 2 measurement along the sidewall of the patient's trachea.

What is claimed is: 
     
       1. A device for assessing the degree of perfusion failure in a patient requiring mechanical ventilatory support, the device comprising: an endotracheal breathing tube comprised of a cannula for carrying air from an air supply pump to the lungs of a patient, the cannula having a proximal end for receiving air from the air supply pump and a distal end having an aperture for releasing air into the patient's trachea; and   carbon dioxide sensor means for detecting the partial pressure of carbon dioxide, with the patient's trachea the sensor means physically connected to the endotracheal breathing tube in a manner that allows for PCO 2  measurement along the sidewall of the patient's trachea.   
     
     
       2. The device of claim 1, further comprising indicator means for indicating the detected partial pressure of carbon dioxide in the patient's trachea, the indicator means operably connected to the carbon dioxide sensor. 
     
     
       3. The device of claim 2, wherein the carbon dioxide sensor comprises a fiber optic PCO 2  sensor. 
     
     
       4. The device of claim 1, wherein the carbon dioxide sensor comprises a fiber optic PCO 2  sensor. 
     
     
       5. The device of claim 1, further including a means for sealing the cannula within the patient's trachea. 
     
     
       6. The device of claim 5, wherein the sealing means comprises an inflatable cuff at the distal end of the cannula. 
     
     
       7. The device of claim 6, further including a means for inflating said cuff. 
     
     
       8. The device of claim 6, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       9. A device for assessing the degree of perfusion failure in a patient requiring mechanical ventilatory support, comprising: an endotracheal breathing tube comprised of a cannula for carrying air from an air supply pump to the lungs of a patient, the cannula having a proximal end for receiving air from the air supply pump and a distal end having an aperture for releasing air into the patient's trachea;   an optical carbon dioxide sensor for detecting the partial pressure of carbon dioxide, within the patient's trachea the sensor physically connected to the endotracheal breathing tube in a manner that allows for PCO 2  measurement along the sidewall of the patient's trachea, wherein the sensor is comprised of an optical fiber means provided with a fluorescent indicator composition;   means for irradiating the indicator composition with light of a predetermined wavelength which causes the indicator composition to emit fluorescent light having an intensity proportional to the PCO 2  value in the region surrounding the sensor; and   means for converting the intensity of the emitted fluorescent light to a value indicative of PCO 2 .   
     
     
       10. The device of claim 9, wherein the irradiating means is capable of irradiating the indicator composition with light of two different wavelengths, and wherein one of the wavelengths is at the isosbestic point. 
     
     
       11. The device of claim 9, wherein the indicator composition is contained within a capsule arranged over the distal tip of the optical fiber means. 
     
     
       12. A method for assessing the degree of perfusion failure in a patient requiring mechanical ventilatory support, comprising: (a) providing an endotracheal breathing tube comprised of a cannula for carrying air from an air supply pump to the lungs of the patient, the cannula having a proximal end for receiving air from the air supply pump and a distal end having an aperture for releasing air into the patient's trachea, the endotracheal breathing tube further including, at the distal end of the cannula, a carbon dioxide sensor means for detecting the partial pressure of carbon dioxide along the sidewall of the patient's trachea;   (b) introducing the distal end of the endotracheal breathing tube into the trachea of the patient so that the carbon dioxide sensor means is positioned against the sidewall thereof; and   (c) detecting the partial pressure of carbon dioxide in the patient's trachea.   
     
     
       13. The method of claim 12, further including determining the degree of perfusion failure in the patient from the detected partial pressure of carbon dioxide in the patient's trachea. 
     
     
       14. The method of claim 12, wherein step (c) is repeated so that the rate of change of the partial pressure of carbon dioxide in the patient's trachea can be determined. 
     
     
       15. The method of claim 14, further including determining the degree of perfusion failure in the patient from the rate of change of the detected partial pressure of carbon dioxide in the patient's trachea. 
     
     
       16. The method of claim 12, further including introducing air from an air supply pump through the cannula and into the patient's trachea after step (b) and prior to or during step (c). 
     
     
       17. The method of claim 16, wherein the endotracheal breathing tube further includes a means for sealing the cannula within the patient's trachea. 
     
     
       18. The method of claim 17, wherein the sealing means comprises an inflatable cuff at the distal end of the cannula. 
     
     
       19. The method of claim 18, further comprising inflating said cuff prior to introduction of air into the patient's lungs. 
     
     
       20. The method of claim 19, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       21. The method of claim 18, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       22. The method of claim 12, wherein the carbon dioxide sensor means comprises a fiber optic PCO 2  sensor. 
     
     
       23. The method of claim 12, wherein the endotracheal breathing tube further includes a means for sealing the cannula within the patient's trachea. 
     
     
       24. The method of claim 23, wherein the sealing means comprises an inflatable cuff at the distal end of the cannula. 
     
     
       25. The method of claim 24, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       26. The method of claim 12, wherein the patient requiring mechanical ventilatory support is a surgery patient requiring general anesthesia. 
     
     
       27. The method of claim 12, wherein the patient requiring mechanical ventilatory support is a neonate. 
     
     
       28. A method for assessing the degree of perfusion failure in a patient requiring mechanical ventilatory support, comprising: (a) providing an endotracheal breathing tube comprised of a cannula for carrying air from an air supply pump to the lungs of the patient, the cannula having a proximal end for receiving air from the air supply pump and a distal end having an aperture for releasing air into the patient's trachea, the endotracheal breathing tube further including, at the distal end of the cannula, an optical carbon dioxide sensor for detecting the partial pressure of carbon dioxide along the sidewall of the patient's trachea, wherein the sensor is comprised of an optical fiber means provided with a fluorescent indicator composition;   (b) positioning the endotracheal breathing tube so that the optical carbon dioxide sensor contacts the sidewall of the patient's trachea;   (c) irradiating the indicator composition with light of a predetermined wavelength so as to cause the indicator composition to emit fluorescent light having an intensity proportional to the PCO 2  value in the region surrounding the sensor means; and   (d) converting the intensity of the emitted fluorescent light to a value indicative of PCO 2 .   
     
     
       29. The method of claim 28, further including determining the degree of perfusion failure in the patient from the detected partial pressure of carbon dioxide in the patient's trachea. 
     
     
       30. The method of claim 28, wherein step (c) is repeated so that the rate of change of the partial pressure of carbon dioxide in the patient's trachea can be determined. 
     
     
       31. The method of claim 30, further including determining the degree of perfusion failure in the patient from the rate of change of the detected partial pressure of carbon dioxide in the patient's trachea. 
     
     
       32. The method of claim 28, further including introducing air from an air supply pump through the cannula and into the patient's trachea after step (b) and prior to or during step (c). 
     
     
       33. The method of claim 32, wherein the endotracheal breathing tube further includes a means for sealing the cannula within the patient's trachea. 
     
     
       34. The method of claim 33, wherein the sealing means comprises an inflatable cuff at the distal end of the cannula. 
     
     
       35. The method of claim 34, further comprising inflating said cuff prior to introduction of air into the patient's lungs. 
     
     
       36. The method of claim 35, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       37. The method of claim 34, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       38. The method of claim 28, wherein the carbon dioxide sensor means comprises a fiber optic PCO 2  sensor. 
     
     
       39. The method of claim 38, wherein the sealing means comprises an inflatable cuff at the distal end of the cannula. 
     
     
       40. The method of claim 39, wherein the carbon dioxide sensor means is affixed to the exterior of the inflatable cuff, whereby upon inflation thereof the sensor means is forcibly positioned against the sidewall of the patient's trachea. 
     
     
       41. The method of claim 28, wherein the endotracheal breathing tube further includes a means for sealing the cannula within the patient's trachea. 
     
     
       42. The method of claim 28, wherein the patient requiring mechanical ventilatory support is a surgery patient requiring general anesthesia. 
     
     
       43. The method of claim 28, wherein the patient requiring mechanical ventilatory support is a neonate.